The present invention relates to packaging machines that form a tubular bag material and deliver product to the interior thereof so that when the tubular bag material is transversely out and scaled discreet bags are formed. More particularly, the present invention relates to the delivery of plastic film to packaging machines.
For example, in the manufacture of bags of snack foods, a tubular bag material is passed through the packaging machine. Product to be packaged is delivered into the interior of the tubular bag material with the tubular bag material then being transversely out and scaled to form discreet bags. Plastic film that forms the bag is passed about a former which forms the tubular bag material. The plastic film is delivered from rolls which are mounted on driven spindles, with the plastic film passing through a film storage device prior to delivery to the former. The film storage device aids maintaining a continuous supply of film to the packaging machine. The film is stored within the device to aid in overcoming fluctuations in the ratio of delivery and the rate of use of the plastic film.
The above-mentioned storage devices have included a pivotally mounted arm with a series of rollers about which the film passes. Pivoting movement of the arm aids in compensating for any differences in the rate of supply and the used rate of the film. These pivotally mounted arms have a number of disadvantages including not being able to determine with required accuracy the amount of material stored in the device and not being able to at all times maintain the correct tension in the film being delivered to the packaging machine.
Further disadvantages include the device occupying considerable space and being difficult to feed film through.
Previous film storage devices are disclosed in Patent Specifications GB2237008, U.S. Pat. Nos. 4,441,664, 5,317,858, JP08-301210 (Publication No. 10-119910), JP08-29 (Publication No. 10-119909), JP10-290828 (Publication No. 2000-118512), JP11-199092 (Publication No. 2001-018920), JP10-053989 (Publication No. 11-245916), GB1089792, U.S. Pat. Nos. 4,315,394, 4,693,053, 4,501,109 and 4,691,499. Each of these previously known devices has a film storage device which essentially includes one or more roller that moves substantially nearly relative to a fixed roller in order to store the film.
Disclosed in U.S. Pat. No. 4,315,394 is a device to tension film. The device includes a slit roller through which the film passes. The slip is spaced from the longitudinal axis of the roller so that angular movement of the roller adjusts the tension in the film. The roller is intended to act as a film storage device so it is relatively small in diameter and has the slip spaced from the longitudinal axis of the roller which would thereby limit the amount of film that can be stored.
It is the object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages.
There is disclosed herein a film storage device to receive film from a roll and to deliver the film to a machine, said device including:
a base which is to be stationary;
a carriage mounted on the base for pivoting movement about a fixed axis relative to the base and having a periphery about which the film is to be wound so as to store portions of the film;
a torque applying member engaging the carriage so as to urge the carriage to pivot about said axis in a predetermined direction; and
a film passage extending through the carriage transversely through said axis and between angularly spaced locations on said periphery so that film in use passes through the passage to be wound about said periphery.
There is further disclosed herein a film storage device to receive film from a roll and to deliver the film to a machine that uses the film, said device including:
a base which is stationary;
a carriage mounted on the base for pivoting movement about a carriage axis and having a periphery about which the film is to be wound so as to store portions of the film, said periphery including a plurality of rollers mounted on the carriage for rotation about axes parallel to said carriage axis;
a torque applying member engaged in a carriage so as to urge the carriage to pivot about said carriage axis in a predetermined direction; and
a film passage extending through the carriage transversely with respect to said carriage axis and between angularly spaced locations on said periphery so that film in use passes through the passage to be wound about said periphery.